Fix Rails 5 alias_method_chain deprecation

[wagenet]

No description provided.

[wagenet]

Test failures are unrelated to my change.

[atd]

Thank you for the pull request @wagenet

Sorry but I have been disconnected from Rails for 3 years and I am not aware on how engine's path are managed in Rails 5

Tests should also be fixed. I have done some work on the travis branch, but an update of the dummy app is needed.

I hope I get some time for it in a couple of weeks. Sorry for that. Of course, a pull request that updates the tests is very welcomed

[gwalshington]

I'm currently running into this issue as well. Any update on this issue?

[wagenet]

@gwalshington my branch should work for now.

[wagenet]

@atd to be clear, this doesn't change how paths are managed, it just changes how the method overwrite happens to not use alias_method_chain.

[wagenet]

I've closed this pull request, but for the time being I will continue to leave the branch if anyone is using it. However, I would recommend not relying upon it in case it gets deleted in the future.